Liquid treatment apparatus

Liquid treatment apparatus comprising:

• a tank for containing a body of liquid;
• a liquid inlet conduit through which liquid containing suspended particles can be delivered to the tank;
• liquid outlet means disposed generally at the level of the surface of said body of liquid and through which clarified liquid can leave the tank;
• sludge outlet means comprising a sump in a bottom wall of the tank for receiving settled particles and from which said particles can be removed as a sludge;
• sludge conveyor means operable to convey settled particles towards said sludge outlet means;
• a thickener tank closely associated with the first-mentioned tank and having a clarified liquid outlet adjacent its upper end, a sludge outlet adjacent its lower end through which settled sludge can be periodically removed from the apparatus, and an inlet intermediate said outlets, said inlets and outlets being below said level of the surface of the body of liquid in the first-mentioned tank;
• a conduit extending from said sump to said thickener tank inlet, whereby the head of liquid above said sump causes sludge and liquid to continuously flow from said sump into said thickener tank, and causes clarified liquid to flow continuously from said thickener tank liquid outlets;
• and,
• means in said thickener tank for promoting thickening of particles in liquid in the tank;
• an inlet member disposed at an inner end of said liquid inlet conduit adjacent said bottom wall of the tank and arranged to direct influent liquid generally vertically upwards in the tank, said inlet member including generally co-axial inner and outer portions each of tubular form extending about a common axis and through which the liquid flows from end to end, said outer portion being of significantly greater cross-sectional area than said inner portion and defining a discharge end of said inlet, whereby some of the energy in liquid flowing through said inlet member is dissipated as the liquid flows from said inner end portion to said outer end portion;
• static mixer means disposed in said inner portion of the inlet member;
• feed means adapted to permit introduction of chemical additives into influent liquid immediately upstream of said static mixer;
• a generally conical partition member disposed in the tank above said inlet and defining a circulation zone below said member, the remainder of the tank outside said partition member defining a relatively quiescent zone for gravity settling of suspended particles;
• a tubular eductor member having open upper and lower ends and disposed in an upright position below said partition member and generally in alignment with said liquid inlet, said eductor member being arranged relative to said inlet so that liquid entering the tank from the inlet flows upwardly in said eductor member and through the open upper end of the member into said circulation zone, and liquid and suspended particles adjacent said open lower end of the eductor member are entrained by said upward flow of liquid, whereby a recirculation of liquid and suspended particles is established below said partition member for promoting flocculation of said particles;
• rotary impeller means disposed adjacent said discharge end of said inlet in the path of liquid flowing through the inlet and adapted to control circulation of liquid and suspended particles in said circulation zone.

In a liquid treatment apparatus which includes a clarifier tank for containing a body of liquid extending to a predetermined liquid level in the tank;

• an inlet for liquid containing suspended particles;
• liquid outlet means disposed generally at said predetermined liquid level and through which clarified liquid can leave the tank;
• means in said tank for promoting settling of said particles from said liquid;
• a sump in a bottom wall of said tank for receiving settled particles in the form of a sludge;
• sludge conveyor means operable to convey settled particles towards said sump;
• the improvement comprising a thickener tank and having a clarified liquid outlet adjacent an upper end of the tank, a sludge outlet adjacent a lower end of the tank, through which settled slude can be periodically removed from the apparatus, and an inlet intermediate said outlets, said inlet and outlets being below said predetermined liquid level in the clarifier tank;
• a conduit extending from said clarifier tank sump to said thickener tank inlet, whereby the head of liquid in the clarifier tank above the sump causes sludge and liquid to continuously flow from said sump into said thickener tank, and causes clarified liquid to flow continuously from said thickener tank liquid outlet;
• means in said thickener tank for promoting thickening of particles in liquid in the tank;
• and,
• means coupling said clarified liquid outlet of the thickener tank into one of said inlet and liquid outlet means of the clarifier tank.